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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.1L >> Diagnostic Trouble Codes >> DTC P0336 - 24X Reference Signal Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to NO START DIAGNOSIS (A-3) in BASIC TESTING article.
  3. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Check for DTCs. If DTC P0336 is set, go to next step. If DTC P0336 is not set, see DIAGNOSTIC AIDS.
  4. Using DVOM, check for battery voltage at crankshaft and camshaft position sensor battery feed terminals. If about battery voltage is present, go to next step. If about battery voltage is not present, go to step 6).
  5. Unplug PCM. Using fused jumper wire, apply battery voltage to PCM harness cam/crank sensor feed circuit terminal. Check for voltage on PCM harness camshaft and crankshaft sensor reference signal high circuit terminals. If about battery voltage is present, go to step 12) If about battery voltage is not present, go to step 7).
  6. Check for open or short to ground in sensor feed circuit from PCM. Check connections at camshaft and crankshaft position sensors and PCM. Repair as necessary. After repairs, go to next step. If no repairs are required, go to step 8).
  7. Check connections at PCM and replace terminals if necessary. After repairs, go to step 15). If no repairs are required, go to next step.
  8. Check connections at crankshaft position sensor reference signal terminals. Repair if necessary and go to step 15). If no repairs are required, go to next step.
  9. Check reference signal circuit for open or short to ground. Repair as necessary and go to step 15). If no repairs are required, go to next step.
  10. Unplug 24X crankshaft position sensor connector and camshaft position sensor connector. Check for continuity between 24X crankshaft position sensor connector reference low (sensor ground) terminal and camshaft position sensor connector reference low (sensor ground) terminal. Then, check for continuity between 24X crankshaft position sensor connector reference low terminal and 3X crankshaft position sensor connector reference low (ground) terminal. The 3X sensor (also referred to as a 7X sensor) is a 2-wire PM generator that is mounted in the side of the engine block. If continuity is not present, repair open circuit as necessary and go to step 12). If no repairs are required, go to next step.
  11. Check for open in 3X crankshaft sensor reference low (ground) circuit. Check for open in splice for reference low circuit. Check PCM and sensor connections. If repairs are necessary, repair and go to step 15). If no repairs are required, go to next step.
  12. Ignition off. Unplug 24X crankshaft sensor connector. Ignition on. Probe sensor low circuit with test light to battery voltage. If test light is on, go to next step. If test light is not on, go to step 14).
  13. Replace 24X crankshaft position sensor. After repair, go to step 15).
  14. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME data as possible. Monitor SPECIFIC DTC info for DTC P0336 until DTC P0336 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.
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